Memory protection with hidden inline metadata

ABSTRACT

Embodiments are directed to memory protection with hidden inline metadata. An embodiment of an apparatus includes processor cores; a computer memory for the storage of data; and cache memory communicatively coupled with one or more of the processor cores, wherein one or more processor cores of the plurality of processor cores are to implant hidden inline metadata in one or more cachelines for the cache memory, the hidden inline metadata being hidden at a linear address level.

TECHNICAL FIELD

Embodiments described herein generally relate to the field of electronicdevices and, more particularly, memory protection with hidden inlinemetadata.

BACKGROUND

“Spectre” induces a system to speculatively perform operations thatwould not occur during correct program execution and which leak private,confidential, and/or secret information. “Meltdown” breaks all of theassumptions inherent in address space isolation and exploitsout-of-order execution to read arbitrary kernel memory locations thatmay include private, confidential, and/or secret information. BothSpectre and Meltdown communicate the illicitly obtained private,confidential, and/or secret information to an adversary via aside-channel. Operating system (OS) and central processing unit (CPU)microcode patch-based mitigations for speculative execution basedvulnerabilities such as Spectre and Meltdown can be improved by makingthe CPU aware of a program's intent by labeling the program data withmetadata so that the hardware can operate on the data with fullknowledge of its bounds, type, current assignment, etc.

Existing and potential hardware and software architectures manifestadditional security vulnerabilities. For example, some architectures maybe susceptible to memory pointers being overwritten. As another example,some architectures may be susceptible to memory pointers manipulation(value added) that cause the pointers to land on a wrong (unauthorized)data object, either in space or in time. As another example, somearchitectures may be limited in the granularity for which they provideprotection. What is needed is a technical solution to these securityvulnerabilities by allowing the hardware to know the software's intent.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments described here are illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings in whichlike reference numerals refer to similar elements.

FIG. 1 is an illustration of insertion of metadata into a cacheline, inaccordance with at least one embodiment described herein;

FIG. 2 is an illustration of insertion of metadata into a cacheline, inaccordance with at least one embodiment described herein;

FIG. 3A is a flowchart to illustrate a process for handling data withhidden inline metadata, in accordance with at least one embodimentdescribed herein;

FIG. 3B is an illustration of memory storage for an apparatus or systemincluding hidden inline metadata, in accordance with at least oneembodiment described herein;

FIG. 4 is a block diagram of a computing environment 400 that reducesthe likelihood of successful side-channel attacks within a centralprocessing unit (CPU) by providing address-based security features formemory within the CPU, in accordance with at least one embodimentdescribed herein;

FIG. 5 illustrates a memory address translation diagram 600 of animplementation of memory tags that may be used to secure memory addresspointers against attacks, in accordance with at least one embodimentdescribed herein;

FIG. 6A illustrates a block diagram of different tag metadataconfigurations for cachelines, in accordance with at least oneembodiment described herein;

FIG. 6B illustrates a block diagram of a virtual memory address thatillustrates that an identification tag may be stored in variouslocations within the virtual memory address;

FIG. 7 is a block diagram of a system for using various memory tags tosecure memory against side-channel attacks, in accordance with at leastone embodiment described herein;

FIG. 8 is a flow diagram of a process for using memory tagging toprovide an isolated environment (“a sandbox”) for untrusted software, inaccordance with at least one embodiment described herein.

DETAILED DESCRIPTION

Embodiments described herein are directed to memory protection withhidden inline metadata.

Described herein are systems and methods for using memory tagging forside-channel defense, memory safety, and sandboxing to reduce thelikelihood of successful side-channel attacks and other exploits, inaccordance with various embodiments. The disclosed system and methodsinclude memory tagging circuitry that is configured to address existingand potential hardware and software architectures securityvulnerabilities, according to various embodiments. The memory taggingcircuitry may be configured to prevent memory pointers beingoverwritten, prevent memory pointer manipulation (e.g., by addingvalues) that cause the pointers to land on a wrong (unauthorized) dataobject in memory space, access a non-current object in time and increasethe granularity of memory tagging to include byte-level tagging incache. The memory tagging circuitry may also be configured to sandboxuntrusted code by tagging portions (e.g., words) of memory to indicatewhen the tagged portions of memory include contain a protected pointer.By co-locating metadata with the same cacheline as its associated dataso that it is immediately available for enforcement, memory taggingcircuitry provides security features while enabling CPUs to continueusing and benefiting from performing speculative operations in a cachecoherent manner. By allowing the hardware to automatically hide themetadata on the same cacheline transparently from software, legacycompatibility can be maintained as software may access virtual/linearmemory contiguously without needing to ignore or skip over metadataregions, while the hardware may still enforce the metadata policies onthe data.

In some embodiments, an apparatus, system, or method provides for memoryprotection with hidden inline metadata. The hidden inline metadata isimplanted within one or more cachelines for a cache. The metadata ishidden at the linear address/virtual address level as memory is seen bysoftware in a contiguous manner, but the metadata is available for thepurposes of memory tagging (such as tag compare with a pointer tag valuein a linear address), capabilities (such as data structure length,permissions), and/or fine grain memory access control as enforced by thehardware.

In some embodiments, hidden inline metadata may include, but is notlimited to, tag storage. In some embodiments, an apparatus, system, orprocess may operate without defining tag storage architecturally.Hardware is to hide tag metadata, with an identifier to indicate whethermetadata is present in a cacheline. In one embodiment a bit (or bits) ina page table entry identifies whether or not a cacheline includes hiddeninline metadata.

The use of the hidden inline metadata may provide multiple advantages inthe operation of an apparatus, system, or process in comparison withconventional technology to provide metadata, including:

Improved performance with a single cycle required access to data andhidden inline metadata;

Cache efficiency, with no additional metadata being required in thecache area;

Memory efficiency with metadata only being included when required;

Precision with both load and store checks being provided; and

Side channel protection with the parallel metadata being present toavoid speculation in data attacks.

An uncore (uncore referring to functions of a microprocessor that arenot within a processor core) memory tagging solution can supportsub-cacheline memory tagging and shifting data within multiple splitcachelines to detect data buffer overflow, use after free, stackoverflow, heap separation, access control, etc. DCD (Data CorruptionDetection) provides a core memory tagging solution using table lookupsfrom linear space. However, in uncore memory tagging there may be issuesregarding precision (regarding a time required to detect/report errors)and ability to detect both underflow and overflow conditionssimultaneously. Further, the latency for uncore configuration of memorytags may be high, requiring non-temporal memory writes or uncachedwrites to update ECC (Error Correction Code) memory. Reading themetadata may also be an issue with an uncore solution. For example, DCDprovides a core solution for memory tagging, but table lookups vialinear mapped memory create latency issues (potentially causing multiplememory accesses to fetch metadata, and associated cache thrashing)and/or require additional caching of tags. Additionally, separating theDCD tables from the memory data requires multiple memory reads,including one read to fetch the data and additional reads to fetch thetable metadata (e.g., memory tags). Requiring serialization for theindependent memory reads causes performance slowdown, whilespeculatively proceeding with the data processing without knowledge ofthe metadata access control policy (e.g. tag match check) may exposeside channel vulnerabilities.

FIG. 1 is an illustration of insertion of metadata into a cacheline, inaccordance with at least one embodiment described herein. As shown inFIG. 1, an apparatus or system 100 includes one or more processors 110,wherein the one or more processors may include a main processor such asa central processing unit (CPU) 112 or other similar unit, and one ormore other processors 114. The one or more other processors 114 mayinclude, but are not limited to, one or more graphics processing units(GPUs) or other types of processors (AI (Artificial Intelligence)accelerator, FPGA (Field Programmable Gate Array), etc.). Each of theone or more processors 110 may include multiple processor cores 116. TheCPU 112 may include elements illustrated for CPU 412 in FIG. 4.

The apparatus or system 100 includes a memory 120 for the storage ofdata, and one or more caches 130 for the storage of data to increasespeed of operation of the processor cores 116 of the one or moreprocessors 110. For example, the one or more processors 110 may storedata elements in any of the one or more caches 130 to provide forincreased efficiency and performance. The caches 130 may include anylevel of cache, such as L1, L2, and/or L3 caches, and may be locatedwithin varying locations within the apparatus or system 100, includingwithin the one or more processors 110. The apparatus or system 100includes other elements not illustrated in FIG. 1, such as elementsillustrated for processor-based device 700 in FIG. 7.

In some embodiments, the one or more processors 110 of the apparatus orsystem 100 are to insert metadata 140 into one or more cachelines 135for storage and transfer of data between the memory 120 and the caches130. In some embodiments, the metadata 140 is inserted as hidden inlinemetadata within the one or more cachelines 135. The metadata 140 ishidden at the linear address/virtual address level as memory is seen bysoftware, but the metadata 140 is present and visible to the physicalhardware and privileged software for the purposes such as memory tagging(such as tag compare with pointer tag value in linear address),capabilities (such as data structure length and permissions), and/orfine grain memory access control.

In some embodiments, an apparatus, system, or process is to provideefficient memory tagging in operation in which metadata lookup, such aslookup of metadata 140, is performed in the same cacheline and samecycle as the data accesses of the cacheline 135 that the metadata 140 isassociated. This allows memory tags to be checked against a memorypointer tag (linear address tag) by a processor pipeline concurrently(at a same or overlapping time) with the data access occurring beforethe processor pipeline removes the tag metadata prior to, for example, aGPR (General Purpose Register) load. Stated in another way, access tothe one or more memory tags of the first cacheline occurs in a sameclock cycle as data access to the cacheline. In some embodiments, theimplementation of hidden inline metadata for one or more cachelinesenables memory tagging to detect use-after-free vulnerabilities(referring to vulnerabilities to attempts to access memory after it hasbeen freed) or overflow/underflow conditions, and to provide other formsof access control at fine granularities. An embodiment offers a highestperformance solution wherein data need not be acted upon speculativelywithout knowledge of the metadata policy for the data.

In some embodiments, implanting metadata within the cacheline 135 itselfmay be utilized to provide efficient lookup of the metadata 140associated with the data on the same cacheline 135, allowing optimalmemory tagging solutions, machine capability, and fine-grain memoryaccess control. In some embodiments, a memory tagging solution may beextended to all of memory 120, and is not limited to small objectallocations that fit within a cacheline. In some embodiments, aprocessor is to automatically skip over the metadata regions of memoryas it is loading or storing linearly addressed data.

FIG. 2 is an illustration of insertion of metadata into a cacheline, inaccordance with at least one embodiment described herein. As shown inFIG. 2, a cacheline 200 includes a data portion 210 and a metadataportion 220. The metadata portion 220 is hidden for purposes ofcontiguous linear address/virtual address operations 240, but may beconditionally visible and available to the physical hardware andprivileged software for operations such as memory tagging, capabilities,and fine grain memory control 250.

In some embodiments, a system may include the following processorinstructions:

StoreTag([in]Address,[in]tag) instruction: A new processor instructioncalled StoreTag to be called by the memory allocator/free (or otherauthorized software routine) to store/set a tag value associated with aparticular memory location (linear address). The StoreTag is thussimilar to a memory poke. The software setting a tag is required to havewrite access to the linear address associated with the tag to set thetag as determined by protected memory (e.g., page table permissions &meta bit). Thus, even though the metadata is hidden, the StoreTaginstruction can update the hidden metadata corresponding to theaddressed data location in memory.

LoadTag([in]address, [out]tag) instruction: A new processor instructioncalled LoadTag to be called by memory allocator (or other authorizedsoftware routine) to retrieve a tag value associated with a particularmemory location (address). LoadTag is similar to a memory peekinstruction. LoadTag may be utilized in connection with debugging andother operations, allowing software to retrieve the hidden metadatastored in memory.

In some embodiments, memory tagging allows software to select the tagbits within a linear address by setting non-canonical bits to the tagvalue (e.g., utilizing a C or C++ pointer). The linear address tags arethen compared with the metadata tags stored in the hidden memory todetermine if the memory access is authorized. For example, to detectuse-after-free exploits, a memory allocation routine (e.g., malloc) isto set the authorized memory tag(s) (StoreTag) for the allocated memorylocation(s), and then provide software with a pointer value containingthe matching tag value (color) addressing the allocated memory buffer.When the software executes and causes the allocated memory to be loaded(e.g., into a processor register or GPR) or stored to memory, theprocessor will first compare the tag value in the pointer (non-canonicalbits of the linear address) with the metadata tag value stored in hiddenmemory for the specified memory location (linear address). Because themetadata tags are co-located with the data (hidden from software), noadditional memory lookups or caching is required to fetch and comparethe stored tag values. In this manner, an efficient solution for memorytagging and access control is provided. Meanwhile, OS kernel/VMM(Virtual Machine Monitor) is provided to access memory without themetadata page table bit set in its memory mapping to page-in/page-outmemory pages including the tag metadata (metadata physical memory islarger than in LA space). Finally, an overflow memory region is used tostore both extra data and metadata that goes beyond a physical pagesize.

FIG. 3A is a flowchart to illustrate a process for handling data withhidden inline metadata, in accordance with at least one embodimentdescribed herein. As illustrated in FIG. 3, for a 64 bit linear address(as an example) there may be a linear address (indicating a location)together with non-canonical value bits, such as 1 B in an example, as acolor tag. As illustrated, the linear address is utilized for a pagetable lookup and TLB (Translation Lookaside Buffer) cache 304. If thenon-canonical/color tag portion is treated as non-canonical reservedvalue, then a general protection exception (#GP) occurs if the value ischanged (or, alternatively, the top byte may be ignored) 302. Otherwise,the linear address tag value may be compared with the metadata valuestored in hidden memory for the associated address.

In an operation, a CPU (or other processor) is to execute a load orstore an instruction for the memory address (the linear address/locationportion) 306. If the memory address is not a metadata page 308, the datais treated as a non-canonical reserve value 302. In some embodiments, adetermination whether the memory address is a metadata page may bedetermined by checking an identifier in a memory or storage, including,for example, checking whether one or more bits in a page table entry(which may be referred to as a metadata bit) are set to indicate thepresence of metadata in a cacheline for the cachelines corresponding tothe associated page. If the memory address is a metadata page, then thecacheline and lookup tags(s) for corresponding slots in the cachelineare loaded based on address index 310. There is then a determinationwhether the stored tag value (of the stored cacheline with tag metadata330) matches the color tag value in the linear address 312. If not, thenan error is indicated with the faulting address 314.

If there is a match 312, then memory access is allowed 316, illustratedas access to a 64 bit processor register 318, and the processor pipelinemerging data slots for register load or memory store (shown as 60bytes). The actual data location may be calculated based on the pageoffset 301, for exampleAddress=PageAddress+PageOffset+(PageOffset/DataBytesPerLine)*MetaDataSize.This is illustrated in FIG. 3A, wherein if (PageOffset+MetadataPage) isless than PageSize, thenAddress=PageAddress+PageOffset+(PageOffset/DataBytesPerLine)*MetaDataSize,However, otherwise there is an overflow condition and lines thatoverflow are accessed at PhysicalAddress plus Offset, and thusPageAddress=OverflowOffset+(PageAddress/PageSize) 324.

If a software bug/vulnerability causes a freed pointer to be used toaccess newly allocated memory for another part of the program, when thenewly stored tag values don't match the tag value in the freed pointer,then the processor will signal an error/exception/fault. Similarly,bounds checking is implicit by using the same tag value for all entriesin the same array and then changing the tag value for adjacent memorylocations that belong to other data structures.

In some embodiments, with a mechanism as illustrated in FIG. 3A, anygranularity of memory tagging is possible, and may be enabled on a pageby page basis. In the above illustration one byte of tag data isutilized to color 15 bytes of data (with ˜6% memory overhead formetadata). Similarly, 4 bit tags could color 8 B of data, etc.,depending on the size and placement of the tag values. The processorpipeline will check and then remove/skip-over tag values from memoryupon loading data into processor registers or buffers. Similarly, theprocessor pipeline will check the tags when storing data, skipping overthe stored tags to complete the data store around the metadata dataregions.

Embodiments are not limited to the specific process flow and operationsillustrated in FIG. 3A. Varying embodiments are possible to process thedata in connection with hidden inline metadata. Further, hidden inlinemetadata is not limited to the storage of tags as illustrated in FIG.3A.

FIG. 3B is an illustration of memory storage for an apparatus or systemincluding hidden inline metadata, in accordance with at least oneembodiment described herein.

In some embodiments, as indicated in FIG. 3B, a bit in the page tableentry identifies pages that contain hidden inline metadata, such as theexample of a size with 128 B larger than 4 KB. The kernel will operatewith page in/page out 4 KB+128 B, thus including the data and hiddeninline metadata. If there is an overflow, for example,(PageOffset+MetadataInPage)<PageSize, an operation is to fetch the nextline in the page from the overflow memory region based on an offset. Forexample, PageAddress=OverflowOffset+(PageAddress/PageSize).

FIG. 4 is a block diagram of a computing environment 400 that reducesthe likelihood of successful side-channel attacks within a centralprocessing unit (CPU) by providing address-based security features formemory within the CPU, in accordance with at least one embodimentdescribed herein. The computing environment 400 reduces the likelihoodof successful side-channel attacks and memory exploits, whileconcurrently enabling the CPU to perform and benefit from performingspeculative operations, according to an embodiment. The computingenvironment 400 may include an adversary 402 coupled to a system 404through one or more networks 406 or one or more physical connections408, according to an embodiment. The adversary 402 may perform one ormore memory exploits or side-channel attacks 410 on the system 404through the networks 406 and/or through the physical connections 408.The system 404 may include one or more of a variety of computingdevices, including, but not limited, to a personal computer, a server, alaptop, a tablet, a phablet, a smartphone, a motherboard with a chipset,or some other computing device, according to various embodiments. Thesystem 404 is configured to protect a CPU 412 against side-channelattacks using a variety of address-based security features that enablethe CPU to safely operate while performing speculative operations.

The adversary 402 may be a computing system, a person, or a combinationof the computing system and a person, which may attempt one or morememory exploits or sides channel attacks on and against the system 404.The adversary 402 may use one or more networks 406 to execute theexploits and side-channel attacks 410. The adversary 402 may also useone or more physical connections 408, such as a memory interpose, memoryprobes, or the like, to read, modify, and/or write to one or more memoryaddresses within the system 404 in order to physically attack the system404. Some of the attacks 410 may include attempting to override apointer, attempting to manipulate up pointer (e.g., add they value topointer to cause the pointer to point to an unintended object or movebeyond the object's bounds), use a freed pointer to access a new object,and the like.

The system 404 is configured to provide a variety of memory-basedsecurity features to protect against the attacks 410, according to anembodiment. The system 404 includes base central processing unit (CPU)412 which is coupled to memory circuitry 414 through one or morecommunications channels 416, according to an embodiment. The CPU 412includes processor cores 418, cache 420, encryption circuitry 422, andintegrity check circuitry 424, according to an embodiment. The CPU 412also includes pointer security circuitry 426 that is configured toexpand memory tag capabilities, reduce or prevent pointer overrideattacks, reduce or prevent pointer manipulation, prevent the reuse offreed pointers and enable byte-granularity memory safety for the CPU412, according to an embodiment.

The CPU 412 may include any number and/or combination of currentlyavailable and/or future developed single- or multi-core centralprocessing units. In embodiments, the CPU 412 may include ageneral-purpose processor, such as a Core® i3, i5, i7, 2 Duo and Quad,Xeon®, ltanium®, Atom®, or Quark® microprocessor, available from Intel®(Intel Corporation, Santa Clara, Calif.). Alternatively, the CPU 412 mayinclude one or more processors from another manufacturer or supplier,such as Advanced Micro Devices (AMD®, Inc.), ARM Holdings® Ltd, MIPS®,etc. The CPU 412 may include a special-purpose processor, such as, forexample, a network or communication processor, compression engine,graphics processor, co-processor, embedded processor, or the like. TheCPU 412 may be implemented as a single semiconductor package or as acombination of stacked or otherwise interconnected semiconductorpackages and/or dies. The CPU 412 may be a part of and/or may beimplemented on one or more substrates using any of a number of processtechnologies, such as, for example, CMOS (Complementary Metal OxideSemiconductor), BiCMOS (Bipolar CMOS) or NMOS (N-type Metal OxideSemiconductor).

The memory circuitry 414 represents one or more of a variety of types ofmemory that may be used in the system 404, according to an embodiment.The memory circuitry 414 may be volatile memory, may be non-volatilememory, or may be a combination of volatile memory and non-volatilememory, according to an embodiment. The volatile memory may includevarious types of random access memory (RAM). The non-volatile memory mayinclude NAND memory, 3D crosspoint (3DXP), phase-change memory (PCM),hard disk drives, and the like, according to an embodiment.

The CPU 412 uses a number of components to move data back and forthbetween the CPU 412 and the memory circuitry 414, according to anembodiment. For example, while operating one or more software programsor while executing various instructions, the processor cores 418 maygenerate new data 428. The processor cores 418 may use a virtual address(a.k.a. Linear Address) 430 the new data 428 to write the new data 428to the cache 420 or to the memory circuitry 414 via a translatedphysical address 434. The new data 428 may be saved in the cache 420 ascache data 432, or may be added to existing cached data 432, accordingto an embodiment. The cached data 432 may have a physical address 434including KeyIDs, tags or additional meta-data 442. The CPU 412 may beconfigured to use the encryption circuitry 422 and an encryptionalgorithm 436 to encrypt the new data 428 and/or the cached data 432prior to saving the new data 428 and/or the cached data 432 to thememory circuitry 414, as encrypted data 438. The CPU 412 may also usethe integrity check circuitry 424 to generate integrity check values (orMessage Authentication Codes/MAC) 440 that are based on the new data428, the translated virtual address 430, the tags 442 for selecting thecryptographic MAC Key 454, and/or the physical address 434, according toan embodiment. The CPU 412 writes the integrity check values 440 to thememory circuitry 414, to enable corruption detection for the encrypteddata 438 (caused, for example, by decrypting the data with using thewrong key).

The CPU 412 may use the pointer security circuitry 426 to providesecurity for the data within the system 404. The pointer securitycircuitry 426 may be configured to detect when the virtual address 430and/or the corresponding translated physical address 434 is beingoverridden, detect when the virtual address 430 and/or the physicaladdress 434 has been manipulated, detect when the virtual address 430and/or the physical address 434 has been used after being freed, providebyte-granularity memory safety through bounds checking, and providedefinitions for use of memory tags, according to various embodimentsdisclosed herein. FIG. 4 and FIG. 9 illustrate example hardwareconfigurations that may be used to support the security featuresprovided by the pointer security circuitry 426. Various different memorytag configurations that may be identified, defined, and/or applied bythe pointer security circuitry 426 to secure the system 404 from theattacks 410, according to various embodiments.

When the processor cores 418 assign (e.g., by executing a softwareprogram) the virtual address 430 to the new data 428, the pointersecurity circuitry 426 may define, insert, or identify one or morememory tags 442 in the virtual address 430, to associate with the newdata 428 to reduce the likelihood of a successful attack.

The virtual address 430 for the new data 428 may include theidentification tag 444 to provide security for the new data 428. Theidentification tag 444 may be colloquially referred to as a color, amemory color, a tag color, and the like. The identification tag 444 mayinclude one or more bits of the virtual address 430. The pointersecurity circuitry 426 may be configured to define where within thevirtual address 430 the identification tag 444 resides or is defined.For example, the pointer security circuitry 426 may define theidentification tag 444 as the 8 most significant bits in the virtualaddress 430. The identification tag 444 may be defined as, for example,bits 56-62 (i.e., 7 bits) of bits 0-63 of the virtual address 430,assuming, as an example, that the length of the virtual address 430 is64 bits.

The physical address 434 for the new data 428 may include the encryptiontag 446 to provide security for the new data 428. The encryption tag 446may include one or more bits of the physical address 434. The pointersecurity circuitry 426 may be configured to define where within thephysical address 434 the encryption tag 446 resides or is defined. Forexample, the pointer security circuitry 426 may define the encryptiontag 446 as the 3 most significant bits in the physical address 434. Theencryption tag 446 may be defined as, for example, bits 59-62 (i.e., 3bits) of bits 0-63 of the physical address 434, assuming, as an example,that the length of the physical address 434 is 64 bits. The physicaladdress may also be smaller than the virtual address, such as 56 bits insize. The encryption tag 446 may be a representation of a key ID 452that is used to look up the encryption key 454 within a key table 456,by the encryption circuitry 422, according to an embodiment. Theencryption tag 446 may also or alternatively be identified using othertechniques, e.g., may be defined within one or more bits in the physicaladdress 434. The encryption tag may be assigned by the processor basedon which VM is executing on a core or thread in a multi-tenant system,or may be determined by the translation of a virtual address into aphysical address via the page tables or extended page tables (EPTs)utilized by a memory management unit to populate virtual to physicaladdress translations via translation lookaside buffers (TLB).

The pointer security circuitry 426 may also include pointer securityinstructions 458 that at least partially provide tag definitions 460.The pointer security instructions 458 may include a number ofinstructions or operations that may be used by the pointer securitycircuitry 426 or the CPU 412 to add a pointer in accordance with the tagdefinitions 560.

FIG. 5 illustrates a memory address translation diagram 600 of animplementation of memory tags that may be used to secure memory addresspointers against attacks, in accordance with at least one embodimentdescribed herein. The memory address translation diagram 500 illustratesa virtual address 502 that includes an identification tag 504 thatoccupies one or more otherwise unused address bits (e.g., non-canonicaladdress bits) and a virtual address 506 for locating data that occupiesa subset of the virtual address 502, according to an embodiment. Thevirtual address 502 may be 64 bits. The identification tag 504 mayoccupy one or more most significant bits, or other bits within thevirtual address 502. The virtual address 506 is translated into aphysical address 508 through a translation lookaside buffer (TLB) 510,according to an embodiment. An encryption tag 514 may be appended to thephysical address 508 to identify one or more encryption keys through thekey table 456 (shown in FIG. 4), according to an embodiment. Theprocessor may select the encryption tag based on what Virtual Machine(VM) or other context is currently executing on a processor thread, orelse determine the encryption tag from a page table walk and theresulting TLB.

Employing the memory tag architecture that is illustrated in the memoryaddress translation diagram 500, within the virtual address 502 and thephysical address 516, may enable the system 404 and/or the centralprocessing unit 412 (shown in FIG. 4) to increase the size ofidentification tags 504 to increase the difficulty of an adversary inguessing which memory tag (e.g., identification tag 504 and/orencryption tag 514) that is associated with a particular memory addresspointer and/or a particular object, according to an embodiment. Guessingthe wrong tag results in faults/exceptions that prevents data disclosurefrom side-channel analysis as speculative execution in an embodiment.

In some embodiments, memory tags are used to secure memory addresspointers against attacks In an operation, a CPU executes a load/storeinstruction for a virtual memory address that includes theidentification tag. Objects within a cacheline may rely on meta-datatags also embedded in the same cacheline to determine if the correctidentification tag in the virtual address was used to access thecorresponding object.

The process further provides for loading a cacheline and looking upmemory tags for corresponding slots in the cacheline, based on anaddress index (e.g., the least significant virtual address bits) and thedata size (indicating the number of tags that need to be checked for thememory access), according to an embodiment. This may be performed afterexecution of the load/store instruction, speculatively before suchoperation, or concurrently with such operation, according to anembodiment. In all cases, the tag meta-data is available to theprocessor residing on the same cacheline, and, thus, does not require aseparate memory load and cache line fill.

The meta-data tags in the cacheline are compared with the identificationtag (e.g., “color” tags) in the virtual address, according to anembodiment. If the tags do not match (are not equal), there is anindication that an error has occurred, according to an embodiment. Ifthe tags match, access to the memory address associated with the loadedcacheline is allowed, according to an embodiment. Notably, the hiddenmetadata allows the object data and the corresponding meta-data tags tooccupy the same cacheline allowing the processor to immediately accessthe tag data and make an access control decision. Contrast this tospeculation which may speculatively proceed with the data access whilewaiting for separate memory loads of meta-data tags to complete,resulting in either side-channels due to speculation or reducedperformance while the processor waits for the separate meta-data load tocomplete.

In some embodiments, a stored cacheline is loaded with objects that maycomprise a number of slots, which are subsets of the cacheline. One ofthe slots of the stored cacheline may include tag metadata, according toan embodiment. The tag metadata may include a tag (e.g., a 1 byteidentification tag) for each of the slots of the stored cacheline,according to an embodiment. The tag metadata provides sub-cachelinegranularity to assign memory tags with memory address pointers or withobjects, to reduce the likelihood of successful attacks.

Memory tags and tag metadata of various sizes, positions and formats maybe used to provide memory tagging security with sub-cachelinegranularity, according to an embodiment. The stored cacheline includes aslot for tag metadata that is associated with 7 slots, according to anembodiment. The slots may include an additional byte or bits of metadatathat may be used to support additional memory tagging functionality,according to an embodiment. There is an extra byte tag for the firstslot, that can be used to access control the first slot containing the 8bytes of meta data (tags), for example, limiting access to the memoryallocation routines that know the correct identification tag to accessthe meta-data slot. Virtual addresses corresponding to the first slotmay be binary bx . . . x000xxx, second slot bx . . . x001xxx, third bx .. . x010xxx, fourth bx . . . x011xxx, etc. In other words, those threeaddress bits third from the least significant address bit determinewhich meta data tag to use based on which slot(s) is being accessed bythe memory reference. The extent of the slots that a data accesscomprises is determined by the instruction or operation being executedby the processor. For example, moving contents from memory to a 64 bitgeneral purpose register in the processor may comprise one 8 byte slot,requiring the checking of the one corresponding meta-data tag, whereasloading a 128 bit XMM register may require checking the tagscorresponding two contiguous slots occupied by the 128 bit SSE data inmemory.

FIG. 6A illustrates a block diagram 600 of different tag metadataconfigurations for cachelines, in accordance with at least oneembodiment described herein. The block diagram 600 includes a firstcacheline 602 and a second cacheline 604. In one implementation of tagmetadata in cachelines, a cacheline such as the first cacheline 602 isconfigured to store a tag metadata in the most significant bits of thecacheline and a cacheline such as the second cacheline 604 is configuredto store tag metadata in the least significant bits of the cacheline.Other slots of the cachelines may be used to store tag metadata,according to various embodiments. This format for hidden meta-dataallows small objects to cross cacheline boundaries in a contiguousfashion, thus allowing incrementing pointers (virtual addresses) toaccess the full extent of objects that may be larger than a singlecacheline. For example, arrays in C or C++ languages are accessed byincrementing the array pointer (virtual address) in a contiguousfashion, allowing the hidden tag meta-data to be verified against thevirtual address identification tag for each slot comprising the array.

Software, such as glibc memory allocator library, is responsible forassigning identification tags and initializing memory. For example, whenmemory is first allocated via the malloc function for a certain size,the malloc function will determine the size. It will then return thevirtual address with this identification tag to the caller.

The malloc routine will identify a freed block of memory, set themeta-data tags to a value corresponding to the pointer's virtual addressidentification tag returning this pointer to the caller. Malloc canaccess and set the hidden tag meta-data by using the LoadTag andStoreTag instructions. Similarly, when freeing allocated memory via thefree routine, the memory manager may access the memory tag location forthe size of the freed memory, setting the hidden tag meta-data toanother value to prevent use-after-free of the previous pointeridentification tags, thus, preventing use-after-free exploits.

FIG. 6B illustrates a block diagram 650 of a virtual memory address 652that illustrates that an identification tag 654 (e.g., a color tag) maybe stored in various locations within the virtual memory address. Theidentification tag 654 may occupy one or more bits within the virtualmemory address 652 such that the virtual memory address 652 includes oneor more bits above the identification tag 654 and one or more bitsbetween the identification tag and the portion of the virtual memoryaddress that is translated into the physical address (e.g., through atranslation lookaside buffer).

FIG. 7 is a schematic diagram of an illustrative electronic,processor-based, device 700 that includes pointer security circuitry 726configured to use various memory tags to secure memory againstside-channel attacks, in accordance with at least one embodimentdescribed herein. The processor-based device 700 may additionallyinclude one or more of the following: one or more processors 710including processor cores 718, cache 720, a graphical processing unit(GPU) 712, a wireless input/output (I/O) interface 720, a wired I/Ointerface 730, memory circuitry 740, power management circuitry 750,non-transitory storage device 760, and a network interface 770. Thefollowing discussion provides a brief, general description of thecomponents forming the illustrative processor-based device 700. Example,non-limiting processor-based devices 700 may include: smartphones,wearable computers, portable computing devices, handheld computingdevices, desktop computing devices, blade server devices, workstations,and similar.

In embodiments, the processor-based device 700 includes processor cores718 capable of executing machine-readable instruction sets 714, readingdata and/or instruction sets 714 from one or more storage devices 760and writing data to the one or more storage devices 760. Those skilledin the relevant art will appreciate that the illustrated embodiments aswell as other embodiments may be practiced with other processor-baseddevice configurations, including portable electronic or handheldelectronic devices, for instance smartphones, portable computers,wearable computers, consumer electronics, personal computers (“PCs”),network PCs, minicomputers, server blades, mainframe computers, and thelike.

The processor cores 718 may include any number of hardwired orconfigurable circuits, some or all of which may include programmableand/or configurable combinations of electronic components, semiconductordevices, and/or logic elements that are disposed partially or wholly ina PC, server, or other computing system capable of executingprocessor-readable instructions.

The processor-based device 700 includes a bus or similar communicationslink 716 that communicably couples and facilitates the exchange ofinformation and/or data between various system components including theprocessor cores 718, the cache 720, the graphics processor circuitry712, one or more wireless I/O interfaces 720, one or more wired I/Ointerfaces 730, one or more storage devices 760, and/or one or morenetwork interfaces 770. The processor-based device 700 may be referredto in the singular herein, but this is not intended to limit theembodiments to a single processor-based device 700, since in certainembodiments, there may be more than one processor-based device 700 thatincorporates, includes, or contains any number of communicably coupled,collocated, or remote networked circuits or devices.

The processor cores 718 may include any number, type, or combination ofcurrently available or future developed devices capable of executingmachine-readable instruction sets.

The processor cores 718 may include (or be coupled to) but are notlimited to any current or future developed single- or multi-coreprocessor or microprocessor, such as: on or more systems on a chip(SOCs); central processing units (CPUs); digital signal processors(DSPs); graphics processing units (GPUs); application-specificintegrated circuits (ASICs), programmable logic units, fieldprogrammable gate arrays (FPGAs), and the like. Unless describedotherwise, the construction and operation of the various blocks shown inFIG. 7 are of conventional design. Consequently, such blocks need not bedescribed in further detail herein, as they will be understood by thoseskilled in the relevant art. The bus 716 that interconnects at leastsome of the components of the processor-based device 700 may employ anycurrently available or future developed serial or parallel busstructures or architectures.

The system memory 740 may include read-only memory (“ROM”) 742 andrandom access memory (“RAM”) 746. A portion of the ROM 742 may be usedto store or otherwise retain a basic input/output system (“BIOS”) 744.The BIOS 744 provides basic functionality to the processor-based device700, for example by causing the processor cores 718 to load and/orexecute one or more machine-readable instruction sets 714. Inembodiments, at least some of the one or more machine-readableinstruction sets 714 cause at least a portion of the processor cores 718to provide, create, produce, transition, and/or function as a dedicated,specific, and particular machine, for example a word processing machine,a digital image acquisition machine, a media playing machine, a gamingsystem, a communications device, a smartphone, or similar.

The processor-based device 700 may include at least one wirelessinput/output (I/O) interface 720. The at least one wireless I/Ointerface 720 may be communicably coupled to one or more physical outputdevices 722 (tactile devices, video displays, audio output devices,hardcopy output devices, etc.). The at least one wireless I/O interface720 may communicably couple to one or more physical input devices 724(pointing devices, touchscreens, keyboards, tactile devices, etc.). Theat least one wireless I/O interface 720 may include any currentlyavailable or future developed wireless I/O interface. Example wirelessI/O interfaces include, but are not limited to: BLUETOOTH®, near fieldcommunication (NFC), and similar.

The processor-based device 700 may include one or more wiredinput/output (I/O) interfaces 730. The at least one wired I/O interface730 may be communicably coupled to one or more physical output devices722 (tactile devices, video displays, audio output devices, hardcopyoutput devices, etc.). The at least one wired I/O interface 730 may becommunicably coupled to one or more physical input devices 724 (pointingdevices, touchscreens, keyboards, tactile devices, etc.). The wired I/Ointerface 730 may include any currently available or future developedI/O interface. Example wired I/O interfaces include, but are not limitedto: universal serial bus (USB), IEEE 1394 (“FireWire”), and similar.

The processor-based device 700 may include one or more communicablycoupled, nontransitory, data storage devices 760. The data storagedevices 760 may include one or more hard disk drives (HDDs) and/or oneor more solid-state storage devices (SSDs). The one or more data storagedevices 760 may include any current or future developed storageappliances, network storage devices, and/or systems. Non-limitingexamples of such data storage devices 760 may include, but are notlimited to, any current or future developed non-transitory storageappliances or devices, such as one or more magnetic storage devices, oneor more optical storage devices, one or more electro-resistive storagedevices, one or more molecular storage devices, one or more quantumstorage devices, or various combinations thereof. In someimplementations, the one or more data storage devices 760 may includeone or more removable storage devices, such as one or more flash drives,flash memories, flash storage units, or similar appliances or devicescapable of communicable coupling to and decoupling from theprocessor-based device 700.

The one or more data storage devices 760 may include interfaces orcontrollers (not shown) communicatively coupling the respective storagedevice or system to the bus 716. The one or more data storage devices760 may store, retain, or otherwise contain machine-readable instructionsets, data structures, program modules, data stores, databases, logicalstructures, and/or other data useful to the processor cores 718 and/orgraphics processor circuitry 712 and/or one or more applicationsexecuted on or by the processor cores 718 and/or graphics processorcircuitry 712. In some instances, one or more data storage devices 760may be communicably coupled to the processor cores 718, for example viathe bus 716 or via one or more wired communications interfaces 730(e.g., Universal Serial Bus or USB); one or more wireless communicationsinterfaces 720 (e.g., Bluetooth®, Near Field Communication or NFC);and/or one or more network interfaces 770 (IEEE 802.3 or Ethernet, IEEE802.11, or WiFi®, etc.).

Processor-readable instruction sets 714 and other programs,applications, logic sets, and/or modules may be stored in whole or inpart in the system memory 740. Such instruction sets 714 may betransferred, in whole or in part, from the one or more data storagedevices 760. The instruction sets 714 may be loaded, stored, orotherwise retained in system memory 740, in whole or in part, duringexecution by the processor cores 718 and/or graphics processor circuitry712.

The processor-based device 700 may include power management circuitry750 that controls one or more operational aspects of the energy storagedevice 752. In embodiments, the energy storage device 752 may includeone or more primary (i.e., non-rechargeable) or secondary (i.e.,rechargeable) batteries or similar energy storage devices. Inembodiments, the energy storage device 752 may include one or moresupercapacitors or ultracapacitors. In embodiments, the power managementcircuitry 750 may alter, adjust, or control the flow of energy from anexternal power source 754 to the energy storage device 752 and/or to theprocessor-based device 700. The power source 754 may include, but is notlimited to, a solar power system, a commercial electric grid, a portablegenerator, an external energy storage device, or any combinationthereof.

For convenience, the processor cores 718, the graphics processorcircuitry 712, the wireless I/O interface 720, the wired I/O interface730, the storage device 760, and the network interface 770 areillustrated as communicatively coupled to each other via the bus 716,thereby providing connectivity between the above-described components.In alternative embodiments, the above-described components may becommunicatively coupled in a different manner than illustrated in FIG.7. For example, one or more of the above-described components may bedirectly coupled to other components, or may be coupled to each other,via one or more intermediary components (not shown). In another example,one or more of the above-described components may be integrated into theprocessor cores 718 and/or the graphics processor circuitry 712. In someembodiments, all or a portion of the bus 716 may be omitted and thecomponents are coupled directly to each other using suitable wired orwireless connections.

FIG. 8 illustrates a flow diagram of a method 800 for using memorytagging to provide an isolated environment (“a sandbox”) for untrustedsoftware, consistent with embodiments of the present disclosure. Theisolated environment may include hardware (e.g., the pointer securitycircuitry 426—shown in FIG. 4) and may include firmware, software, orother instructions (e.g., the pointer security instructions 458—shown inFIG. 4).

At operation 802, the method 800 allocates one or more bits in acacheline to define a protected pointer tag to indicate whether datawithin the cacheline includes a protected memory address pointer,according to an embodiment. The data within the cacheline may be a wordof data.

At operation 804, the method 800 receives a request to modify a memoryaddress pointer, according to an embodiment.

At operation 806, the method 800 reads the protected pointer tag for thememory address pointer to determine if the memory address pointer isprotected, according to an embodiment.

At operation 808, the method 800 determines whether the protectedpointer tag is set, according to an embodiment. If the protected pointertag is not set, operation 808 proceeds to operation 810. If theprotected pointer tag is set, operation 808 proceeds to operation 812.

At operation 810, the method 800 grants the request to modify the memoryaddress pointer, according to one embodiment.

At operation 812, the method 800 determines whether the request tomodify the memory address pointer was made with authorized pointersecurity instructions. If the request was made with authorized pointersecurity instructions, operation 812 proceeds to operation 810, wherethe request is granted. If the request was not made with authorizedpointer security instructions, operation 812 proceeds to operation 814,wherein the request is denied.

Embodiments of the disclosed technology may be used to sandbox untrustedsoftware. Other usages described herein (memory tagging, capabilities,integrity, etc.) may also be applied to various memory data types(float, integer, string, stack pointer, return address, etc.), controlregisters (CR3 (used in relation to translating linear addresses intophysical addresses), IDTR (Interrupt Descriptor Table Register)), bufferlength (off-by-one byte detection), and Integrity Check Value/MAC(detects memory corruption).

In some embodiments, an apparatus includes a plurality of processorcores; a computer memory for storage of data; and cache memorycommunicatively coupled with one or more of the processor cores, whereinone or more processor cores of the plurality of processor cores are toimplant hidden inline metadata in one or more cachelines for the cachememory, the hidden inline metadata being hidden at a linear addresslevel.

In some embodiments, the hidden inline metadata is available forpurposes for one or more of memory tagging, identification ofcapabilities, and fine grain memory access control.

In some embodiments, the apparatus further includes pointer securitycircuitry to define a plurality of memory tags in memory addresspointers; and encryption circuitry to cryptographically secure dataobjects at least partially based on the plurality of memory tags,wherein the hidden inline metadata for a first cacheline includes one ormore memory tags.

In some embodiments, the one or more processor cores are further tocompare the one or more memory tags in the hidden inline metadata forthe first cacheline with a memory pointer tag value in a linear addressto determine whether a memory access is authorized.

In some embodiments, the one or more processor cores to compare the oneor more memory tags of the first cacheline with the memory pointer tagat a same or overlapping time with data access to the cacheline.

In some embodiments, software run by the plurality of processor coresare to skip over one or more regions of memory for the metadata insertedin the one or more cachelines during loading or storing of linearaddressed data.

In some embodiments, the one or more processor cores are to set anindicator in a memory or storage to indicate presence of the hiddeninline metadata in the one or more cachelines.

In some embodiments, the indicator includes one or more bits of a pagetable.

In some embodiments, one or more non-transitory computer-readablestorage mediums having stored thereon executable computer programinstructions that, when executed by one or more processors, cause theone or more processors to perform operations including implanting hiddeninline metadata for one or more memory tags memory tags in one or morecachelines for a cache memory, the hidden inline metadata being hiddenat a linear address level; and setting an indicator to indicate presenceof the hidden inline metadata in the one or more cachelines.

In some embodiments, the instructions include instructions for utilizingthe hidden inline metadata for one or more of memory tagging,identification of capabilities, and fine grain memory access control.

In some embodiments, the instructions include instructions for utilizingthe memory tags to detect one or more of use-after-free vulnerabilitiesor overflow/underflow conditions.

In some embodiments, the instructions include instructions for definingone or more memory tags in memory address pointers; andcryptographically securing data objects at least partially based on oneor more of the memory tags, wherein the hidden inline metadata for afirst cacheline includes one or more memory tags.

In some embodiments, the instructions include instructions for comparingthe one or more memory tags in the hidden inline metadata for the firstcacheline with a memory pointer tag value in a linear address anddetermining whether a memory access is authorized based at least in parton the comparison of the one or more memory tags to the memory pointertag.

In some embodiments, access to the one or more memory tags of the firstcacheline occurs in a same clock cycle as data access to the cacheline.

In some embodiments, one or more regions of memory for the metadatainserted in the one or more cachelines are skipped during loading orstoring of linear addressed data.

In some embodiments, the instructions include instructions for settingan indicator in a memory or storage to indicate presence of the hiddeninline metadata in the one or more cachelines.

In some embodiments, the indicator includes one or more bits of a pagetable.

In some embodiments, a method includes implanting hidden inline metadatafor one or more memory tags memory tags in one or more cachelines for acache memory, the hidden inline metadata being hidden at a linearaddress level; and setting an indicator to indicate presence of thehidden inline metadata in the one or more cachelines.

In some embodiments, the method further includes utilizing the hiddeninline metadata for one or more of memory tagging, identification ofcapabilities, and fine grain memory access control.

In some embodiments, the method further includes utilizing the memorytags to detect one or more of use-after-free vulnerabilities oroverflow/underflow conditions.

In some embodiments, the method further includes defining one or morememory tags in memory address pointers; and cryptographically securingdata objects at least partially based on one or more of the memory tags,wherein the hidden inline metadata for a first cacheline includes one ormore memory tags.

In some embodiments, the method further includes comparing the one ormore memory tags in the hidden inline metadata for the first cachelinewith a memory pointer tag value in a linear address; and determiningwhether a memory access is authorized based at least in part on thecomparison of the one or more memory tags to the memory pointer tag.

In some embodiments, access to the one or more memory tags of the firstcacheline occurs in a same clock cycle as data access to the cacheline.

In some embodiments, the method further includes skipping one or moreregions of memory for the metadata inserted in the one or morecachelines during loading or storing of linear addressed data.

In some embodiments, the method further includes setting an indicator ina memory or storage to indicate presence of the hidden inline metadatain the one or more cachelines.

In some embodiments, an apparatus includes means for implanting hiddeninline metadata for one or more memory tags memory tags in one or morecachelines for a cache memory, the hidden inline metadata being hiddenat a linear address level; and means for setting an indicator toindicate presence of the hidden inline metadata in the one or morecachelines.

In some embodiments, the apparatus further includes means for utilizingthe hidden inline metadata for one or more of memory tagging,identification of capabilities, and fine grain memory access control.

In some embodiments, the apparatus further includes means for utilizingthe memory tags to detect one or more of use-after-free vulnerabilitiesor overflow/underflow conditions.

In some embodiments, the apparatus further includes means for definingone or more memory tags in memory address pointers; and means forcryptographically securing data objects at least partially based on oneor more of the memory tags, wherein the hidden inline metadata for afirst cacheline includes one or more memory tags.

In some embodiments, the apparatus further includes means for comparingthe one or more memory tags in the hidden inline metadata for the firstcacheline with a memory pointer tag value in a linear address; and meansfor determining whether a memory access is authorized based at least inpart on the comparison of the one or more memory tags to the memorypointer tag.

In some embodiments, access to the one or more memory tags of the firstcacheline occurs in a same clock cycle as data access to the cacheline.

In some embodiments, the means for skipping one or more regions ofmemory for the metadata inserted in the one or more cachelines duringloading or storing of linear addressed data.

In some embodiments, the apparatus further includes means for setting anindicator in a memory or storage to indicate presence of the hiddeninline metadata in the one or more cachelines.

In the description above, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the described embodiments. It will be apparent,however, to one skilled in the art that embodiments may be practicedwithout some of these specific details. In other instances, well-knownstructures and devices are shown in block diagram form. There may beintermediate structure between illustrated components. The componentsdescribed or illustrated herein may have additional inputs or outputsthat are not illustrated or described.

Various embodiments may include various processes. These processes maybe performed by hardware components or may be embodied in computerprogram or machine-executable instructions, which may be used to cause ageneral-purpose or special-purpose processor or logic circuitsprogrammed with the instructions to perform the processes.Alternatively, the processes may be performed by a combination ofhardware and software.

Portions of various embodiments may be provided as a computer programproduct, which may include a computer-readable medium having storedthereon computer program instructions, which may be used to program acomputer (or other electronic devices) for execution by one or moreprocessors to perform a process according to certain embodiments. Thecomputer-readable medium may include, but is not limited to, magneticdisks, optical disks, read-only memory (ROM), random access memory(RAM), erasable programmable read-only memory (EPROM),electrically-erasable programmable read-only memory (EEPROM), magneticor optical cards, flash memory, or other type of computer-readablemedium suitable for storing electronic instructions. Moreover,embodiments may also be downloaded as a computer program product,wherein the program may be transferred from a remote computer to arequesting computer.

Many of the methods are described in their most basic form, butprocesses can be added to or deleted from any of the methods andinformation can be added or subtracted from any of the describedmessages without departing from the basic scope of the presentembodiments. It will be apparent to those skilled in the art that manyfurther modifications and adaptations can be made. The particularembodiments are not provided to limit the concept but to illustrate it.The scope of the embodiments is not to be determined by the specificexamples provided above but only by the claims below.

If it is said that an element “A” is coupled to or with element “B,”element A may be directly coupled to element B or be indirectly coupledthrough, for example, element C. When the specification or claims statethat a component, feature, structure, process, or characteristic A“causes” a component, feature, structure, process, or characteristic B,it means that “A” is at least a partial cause of “B” but that there mayalso be at least one other component, feature, structure, process, orcharacteristic that assists in causing “B.” If the specificationindicates that a component, feature, structure, process, orcharacteristic “may”, “might”, or “could” be included, that particularcomponent, feature, structure, process, or characteristic is notrequired to be included. If the specification or claim refers to “a” or“an” element, this does not mean there is only one of the describedelements.

An embodiment is an implementation or example. Reference in thespecification to “an embodiment,” “one embodiment,” “some embodiments,”or “other embodiments” means that a particular feature, structure, orcharacteristic described in connection with the embodiments is includedin at least some embodiments, but not necessarily all embodiments. Thevarious appearances of “an embodiment,” “one embodiment,” or “someembodiments” are not necessarily all referring to the same embodiments.It should be appreciated that in the foregoing description of exemplaryembodiments, various features are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure and aiding in the understanding of one ormore of the various novel aspects. This method of disclosure, however,is not to be interpreted as reflecting an intention that the claimedembodiments requires more features than are expressly recited in eachclaim. Rather, as the following claims reflect, novel aspects lie inless than all features of a single foregoing disclosed embodiment. Thus,the claims are hereby expressly incorporated into this description, witheach claim standing on its own as a separate embodiment.

What is claimed is:
 1. An apparatus comprising: a plurality of processorcores; a computer memory for storage of data; and cache memorycommunicatively coupled with one or more of the processor cores; whereinone or more processor cores of the plurality of processor cores are toimplant hidden inline metadata in one or more cachelines for the cachememory, the hidden inline metadata being hidden at a linear addresslevel.
 2. The apparatus of claim 1, wherein the hidden inline metadatais available for purposes of one or more of memory tagging,identification of capabilities, and fine grain memory access control. 3.The apparatus of claim 1, further comprising: pointer security circuitryto define a plurality of memory tags in memory address pointers; andencryption circuitry to cryptographically secure data objects at leastpartially based on the plurality of memory tags; wherein the hiddeninline metadata for a first cacheline includes one or more memory tags.4. The apparatus of claim 3, wherein the one or more processor cores arefurther to compare the one or more memory tags in the hidden inlinemetadata for the first cacheline with a memory pointer tag value in alinear address to determine whether a memory access is authorized. 5.The apparatus of claim 4, wherein the one or more processor cores tocompare the one or more memory tags of the first cacheline with thememory pointer tag at a same or overlapping time with data access to thecacheline.
 6. The apparatus of claim 1, wherein software run by theplurality of processor cores is to skip over one or more regions ofmemory for the metadata inserted in the one or more cachelines duringloading or storing of linear addressed data.
 7. The apparatus of claim1, wherein the one or more processor cores are to set an indicator in amemory or storage to indicate presence of the hidden inline metadata inthe one or more cachelines.
 8. The apparatus of claim 7, wherein theindicator includes one or more bits of a page table.
 9. One or morenon-transitory computer-readable storage mediums having stored thereonexecutable computer program instructions that, when executed by one ormore processors, cause the one or more processors to perform operationscomprising: implanting hidden inline metadata for one or more memorytags memory tags in one or more cachelines for a cache memory, thehidden inline metadata being hidden at a linear address level; andsetting an indicator to indicate presence of the hidden inline metadatain the one or more cachelines.
 10. The one or more mediums of claim 9,wherein the instructions include instructions for utilizing the hiddeninline metadata for one or more of memory tagging, identification ofcapabilities, and fine grain memory access control.
 11. The one or moremediums of claim 9, wherein the instructions include instructions for:utilizing the memory tags to detect one or more of use-after-freevulnerabilities or overflow/underflow conditions.
 12. The one or moremediums of claim 9, wherein the instructions include instructions for:defining one or more memory tags in memory address pointers; andcryptographically securing data objects at least partially based on oneor more of the memory tags; wherein the hidden inline metadata for afirst cacheline includes one or more memory tags.
 13. The one or moremediums of claim 12, wherein the instructions include instructions for:comparing the one or more memory tags in the hidden inline metadata forthe first cacheline with a memory pointer tag value in a linear address;and determining whether a memory access is authorized based at least inpart on the comparison of the one or more memory tags to the memorypointer tag.
 14. The one or more mediums of claim 13, wherein access tothe one or more memory tags of the first cacheline occurs in a sameclock cycle as data access to the cacheline.
 15. The one or more mediumsof claim 9, wherein one or more regions of memory for the metadatainserted in the one or more cachelines are skipped during loading orstoring of linear addressed data.
 16. The one or more mediums of claim9, wherein the instructions include instructions for: setting anindicator in a memory or storage to indicate presence of the hiddeninline metadata in the one or more cachelines.
 17. The one or moremediums of claim 16, wherein the indicator includes one or more bits ofa page table.
 18. A method comprising: implanting hidden inline metadatafor one or more memory tags memory tags in one or more cachelines for acache memory, the hidden inline metadata being hidden at a linearaddress level; and setting an indicator to indicate presence of thehidden inline metadata in the one or more cachelines.
 19. The method ofclaim 18, further comprising utilizing the hidden inline metadata forone or more of memory tagging, identification of capabilities, and finegrain memory access control.
 20. The method of claim 18, furthercomprising: utilizing the memory tags to detect one or more ofuse-after-free vulnerabilities or overflow/underflow conditions.
 21. Themethod of claim 18, further comprising: defining one or more memory tagsin memory address pointers; and cryptographically securing data objectsat least partially based on one or more of the memory tags; wherein thehidden inline metadata for a first cacheline includes one or more memorytags.
 22. The method of claim 21, further comprising: comparing the oneor more memory tags in the hidden inline metadata for the firstcacheline with a memory pointer tag value in a linear address; anddetermining whether a memory access is authorized based at least in parton the comparison of the one or more memory tags to the memory pointertag.
 23. The method of claim 22, wherein access to the one or morememory tags of the first cacheline occurs in a same clock cycle as dataaccess to the cacheline.
 24. The method of claim 18, further comprising:skipping one or more regions of memory for the metadata inserted in theone or more cachelines during loading or storing of linear addresseddata.
 25. The method of claim 18, further comprising: setting anindicator in a memory or storage to indicate presence of the hiddeninline metadata in the one or more cachelines.